The present invention relates to a hoist device which can be used to lift a variety of heavy loads or objects such as dies, vehicles, internal combustion engines, etc. and it will be described with particular reference thereto; however, the invention has much broader applications and may be used for a variety of applications where it is necessary to secure a ring to a structure either to lift the structure or to for hold down a structure such as containers, airplanes, air vehicles, boats, etc.
The least expensive hoist device of the type to which the present invention is directed, is a standard eye bolt which is a ring cast with a depending shank which is threaded to be received in a threaded bore provided on the member to be lifted or hoisted. A mechanical hoist having a line with a hook is then used to lift the device by applying the hook through the eye bolt and operating the hoist device. Since an eye bolt is quite inexpensive, it is generally used in most high production applications such as motors, welders, generators, combustion engines, etc. Such commodities are provided with eye bolts so that they can be hoisted and maneuvered into the desired position. The difficulty with the eye bolt is that it cannot compensate for lifting forces which are not actually aligned with the axis of the shank on the eye bolt. Thus, the eye bolts are usually made relatively heavy to compensate for the lack of versatility of the eye bolts.
Through the years, a large number of hoist devices have been developed which allow for the ring connected to the hook of the hoist to pivot and swivel for the purpose of automatically adjusting the disposition of the ring with respect to the force being applied by the hoist during the lifting procedure. Such devices are found in the patents incorporated by reference herein and all are extremely expensive. In addition, they generally have disadvantages. These prior devices cannot be easily disassembled and tested in the field. In addition, if they are assembled differently, they react and operate differently. Thus, they cannot be easily tested after use or reassembled and operate consistently. The reason for these disadvantages is because of the complexity of the structure necessary for accomplishing the swivel action. In addition, these devices utilize a clevis which is less strong than the continuous ring of an eye bolt.
The use of a clevis has been dictated by the structure necessary for accomplishing the swivel action in the prior devices. The swivel action is accomplished by a stud clamping a ring against a bushing. The bushing defines a track or guideway for a support ring to swivel about a bolt. In using such structures, the only manner in which a ring can be mounted to the support ring that can swivel is by employing a clevis construction. Such constructions are extremely expensive and cannot be disassembled and tested in the field. The weight and cross-section of the clevis must be such that it cannot be pulled away from the swivel ring mechanism. All of these requirements of the prior hoist rings which allow both swivel movement of the ring while also allowing the ring to move or pivot about the pins of the clevis contribute to the extreme cost, complexity, inability to disassemble or reassemble and test, and related problems.